biodiesel

there are several types of biodiesel, and it really depends where the fuel is coming from, and the process used to refine it to automotive-grade fuel. some biodiesels are designed to be loaded along with the regular diesel fuel. they say that it helps clean your fuel system, as well as the pistons, removing carbon deposits, and generally providing a cleaner burn. this type of biodiesel is designed for use with non-modified diesel engines, and mixed with regular diesel. another would be the straight-shot used cooking oil, though i don't know the mechanics on this one, the gist of this is that they use regular diesel during starting, and then switch fuel cells while running. and it gives your engine that nice mcdonald's fryer smell. :) makes you hungry just smelling your exhaust. personally, i would recommend the type that just goes in with the regular diesel. btw, you can make your own if you're so inclined.

Engines that use bio-diesel can still run on regular diesel fuel as well. We have friends in Indiana who have a truck that runs on bio-diesel, but they can fill up with regular diesel fuel if the bio-diesel is not available. As more vehicles are converted, more stations will begin carrying it and the price will probably eventually come down with increased competition and production (law of supply and demand, you know). Presently, bio-diesel prices are pretty close to that of standard fuel, since most companies are still trying to recoup their initial investiment to produce bio-fuels.